阈值分割算子之OSTU算法

1、原理参考：https://www.cnblogs.com/guopengfei/p/4759569.html

2、公式推导：

      

3、同halcon的binary_threshold (Image, Region, 'max_separability', 'light', UsedThreshold3)算子。

    具体推导如下：

 gray_histo (Region, Image, AbsoluteHisto, RelativeHisto)
 nAveragray:=0
 for Index := 0 to 255 by 1
     nAveragray:=nAveragray+RelativeHisto[Index]*Index 
 endfor
 wk:=0.0
 uk:=0.0
 MaxDiff:=0.0
 Diff:=0.0
 AutoThre:=0

 for Index := 0 to 255 by 1
     wk:=wk+RelativeHisto[Index]
     uk:=uk+RelativeHisto[Index]*Index
     if(wk<=0.0 or wk>=1.0)
          Diff:=0
     else
          Diff:=(nAveragray*wk-uk)*(nAveragray*wk-uk )/(wk*(1-wk))
     endif
     if(Diff>MaxDiff)
           MaxDiff:=Diff
           AutoThre:=Index
     endif
 endfor

　　

 

来源：https://www.cnblogs.com/baiyy-daheng/p/11421537.html